Cisco 400-007 Exam With Confidence Using Practice Dumps

B (Northbound APIs):Northbound APIs allow applications to communicate with the SDN controller to express service requests and provide policy intent. The controller translates these into instructions for the underlying infrastructure.

Other options explained:

A: Southbound APIs connect controllers to forwarding devices.

C: Orchestration coordinates workflows across domains but doesn’t directly connect applications to controllers.

D: The SDN controller receives the northbound API calls but is not the API itself.

OSPF uses pacing timers to control how quickly it sends LSAs to neighbors to prevent network flooding and CPU spikes:

C. Retransmission-pacing timer: Controls spacing between retransmitted LSAs queued after a lost or unacknowledged transmission.

E. Flood-pacing timer: Controls spacing between consecutive LSAs when flooding new information to peers.

These timers are critical in scaling OSPF in dense or unstable topologies and are key to tuning control plane convergence performance without destabilizing routers.

To achieve sub-50ms protection against both link and node failures, MPLS TE Fast Reroute (FRR) with Next-Next-Hop (NNHop) protection is used:

Next-Next-Hop tunnels provide node protection by pre-establishing a detour that bypasses not only the immediate next-hop link but also the entire next node.

This ensures protection for both link and node failures, matching SONET/SDH resiliency targets.

Other options explained:

A and C: TE backup and FRR backup tunnels may only provide link protection depending on deployment.

B: Next-Hop tunnels address only link failures, not node failures.